Burner apparatus and method for manufacturing of glass wool

ABSTRACT

This invention relates to a method and apparatus for forming glass fibers by remelting primary filaments from a melting furnace by means of a high velocity jet uniform flame of increased with but with a lower width ratio of unused flame ends to total flame width. This is accomplished by placing a plurality of new burner units in a side by side relation while in communication with the combustion chamber. Each burner unit comprises a flame holder utilizing converging stream of combustible gas surrounded by a spiral configurated stream around both a which is enveloped a third stream.

Maf c'hzo, 1973 K|wAMU QKUMA ErAL 3,721,538

BURNER APPARATUS AND METHOD FOR MANUFACTURING OF GLASS WOOL 2 Sheets-Sheet 1 Filed Dec. 22, 1971 KIWAAMU OKU MA TA K E O A BE INVENTORS BQ FM 99W March 20, 1973 KIWAMU OKUMA ETAL 3,721,513

BURNER APPARATUS AND METHOD FOR MANUFACTURING OF GLASS WOOL Filed Dec. 22, 1971 2 Sheets-Sheet 2 Fig.2

United States Patent Oflice 3,721,538 Patented Mar. 20, 1973 3,721,538 BURNER APPARATUS AND METHOD FOR MANUFACTURING F GLASS WOOL Kiwamu Olruma and Takeo Abe, Kon'yama, Japan, as-

signors to Paramount Glass Mfg. Co., Ltd., Koriyama City, Fukushima-ken, Japan Filed Dec. 22, 1971, Ser. No. 210,768 Claims priority, application Japan, Dec. 23, 1970, 45/116,972 Int. Cl. C03b 37/06 U.S. Cl. 65-7 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a method and apparatus for forming glass fibers by remelting primary filaments from a melting furnace by means of a high velocity jet uniform flame of increased width but with a lower width ratio of unused flame ends to total flame width. This is accomplished by placing a plurality of new burner units in a side by side relation while in communication with the combustion chamber. Each burner unit comprises a flame holder utilizing converging streams of combustible gas surrounded by a spiral configurated stream around both of which is enveloped a third stream.

SUMMARY OF THE INVENTION This invention relates to a method and apparatus for forming fibers by remelting the primary filaments obtained from a melting furnace.

In the conventional jet method of forming fibers from glass primary filaments the jet burner employs a tapered jet flame orifice which ejects a high temperature flame under a high velocity.

To obtain this high temperature jet flame under high velocity it is necessary to burn a gaseous mixture of considerable amounts of air and fuel in a narrow combustion chamber and supply the gaseous mixture at a very high velocity which exceeds (less than 5 m./s. in turbulent flow) the necessary flame transmission velocity for continuous stable combustion. If there is incomplete combustion, the unburned gas burns on the outside of the combustion chamber jet orifice. This decreases the gas burner jet flame temperature and velocity and results in a lessening of the gas burner fiberizing efficiency. Further, if the pattern of the flame in the combustion chamber is unstable it will cause noise and pulsative variation in jet flame temperature and velocity which will obviously lower the manufactured glass wool quality.

In manufacturing glass wool by the jet burner method, the glass primary filaments are arranged in a row against the jet flame ejecting from the gas burner. The flame is wider than the length of the row of the primary filaments so that each end of the flame is not used for forming fibers. Therefore, in order to promote flame utilization efliciency, the number of primary filaments is increased along with the flame width while diminishing the width ratio of both ends to the total flame width. Increasing the flame width in such a way will result in increasing glass wool production. However, by increasing the width of the flame it becomes diflicult to obtain uniform flame throughout the width thereof.

Further, the combustion chamber is exposed to high temperatures at all times which reduces the service life of the refractory material. In addition, the mixed gas sup ply section is designed to prevent back fire and stabilize combustion by a beehive screen (less than 6 mm. diameter holes and over mm. thickness screen) which requires from 2 kg./cm. 0.5 kg./cm. compressed air. This results in a sizable investment in both equipment and power.

It is, therefore, an object of this invention to obtain a stable flame temperature and a stable velocity by increasing the width of the flame jet to the structurally permissible limit in the combustion chamber.

Another object of this invention is to obtain a stable ignition source by utilizing a part of the supplied mixed gas itself to maintain the flame of a flame holder and simultaneously cool the combustion chamber and the flame holder thereby preventing back fire, and making it possible to use comparatively low pressure compressed air which results in a lower investment for both equipment and power.

BRIEF DESCRIPTION OF THE DRAWINGS These, together with other objects, will become more fully apparent upon reference to the following description.

In the drawings:

FIG. 1 is a side view showing a glass wool manufacturing device utilizing a jet burner with a portion in section;

FIG. 2 is a vertical section view of the device of this invention;

FIG. 3 is a sectional view taken substantially along line -III-III of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. 1, primary filaments 102 are drawn from melting furnace 101 by roller 103, pass through guide 104 and introduced into jet flame 106 ejecting from gas burner 105, whereby they are attenuated into fibers 107 and collected by the collection chamber 108. Thereafter the fibers enter the curing oven 10 9 in mat form and are wound into rolls by roll up machine 110.

Gas burner as shown in FIG. 2 in section, provides multiple gas burner units 1 arranged in a row widthwise of the combustion chamber 4. Gas burner units 1 are fixed by bolts 42 to the combustion chamber wall 41 and insulated therefrom by water cooling tube 9'. Each gas burner unit 1 is composed of a cylindrical main body 11 defining a chamber 3 through which mixed gas passes and flame holder 2 inside main body 11. Flame holder 2 defining a chamber 20 therein is fixed to the tip of cyl indrical tube 30 positioned within the main body 11. At end 23 of flame holder 2 (FIG. 3) a spark plug 7 is provided which is connected to a source of power by an electrical wire passing through tube 51.

Referring now to FIG. 3, flame holder 2 has a cylindrical wall 24 through which are drilled tangentially to chamber 20 uniformly spaced holes 21 connecting chamber 20 and the interior of cylindrical body 30. End 23 of flame holder 2 defines uniformly spaced small holes 22 connecting chamber 20 and the interior of cylindrical body 30. Streams of gas pass through small holes 22 into chamber 20 and collide with each other at position V in front of ignition spark plug 7. Upon collison they lose their kinetic energy and disperse uniformly. Cylindrical body 30 is threadably connected to pressurized mixed gas supply pipe 5 and to cylindrical main body 11 by means of nut 32. Cylindrical body 30 defines holes 31 to interconnect chamber 3 with a source of gas not shown.

Flame holder 2 has outlet 25 located substantially at the connection of combustion chamber 4, cooling tube 9 and mixed gas supply chamber 3. Combustion chamber 4 has outer walls 43, 45 and 46 surrounding refractory material 41 which are connected to each other by bolts 44. Closure 52 supports tube 51 and serves to close the end 53 of mixed gas supply pipe 5.

One advantage of this apparatus is the obtaining of a uniform flame. A wider more stable flame is provided by multiple gas burner units generating stable flame in one combustion chamber. Adjustments of temperature and velocity of the entire flame throughout the width of the combustion chamber are made at each individual gas burner unit.

Another advantage is the provision of a small stable primary flame in the flame holder chamber in each gas burner unit which ignites the spirally flowing mixed gas. The spirally formed flame obtained by such means is the secondary flame which ignites uniformly the considerable amount of air and gas mixture.

The most important role of the primary flame is to exist as a stable flame. The most important role of the secondary flame is to ignite uniformly the considerable amount of mixed gas.

The unburned mixed gas passing through chamber 3 is supplied as though covering the inner walls of the combustion chamber. Even though it covers the inner walls, the mixed gas will have completed combustion by the time it reaches the orifice of the combustion chamber.

A portion of the supplied mixed gas is utilized to create the primary and secondary flames, while the remainder of the mixed gas is utilized to maintain the flame holder by cooling the flame holder and preventing a back fire.

From 0.60.8% of the mixed gas G supplied from supply pipe 5 to each burner unit and small holes 22 passes into flame holder chamber 20 to collide at position V of chamber 20 at which point the streams lose their velocity and are ignited by spark plug 7. The small holes need not be limited to 4 holes, so long as there are enough holes properly directed, to force the colliding streams to lose their velocity.

Upon ignition by spark plug 7 a portion of the mixed gas supplied continuously from small holes 22, will maintain a stable small flame at position V.

Another portion of the mixed gas G will pass into flame holder chamber 20 through holes 21 of flame holder 2. Likewise, holes 21 are not necessarily limited to 4. The amount of mixed gas introduced is about 34% of the total amount supplied to each burner unit.

The mixed gas introduced into flame holder chamber 20 adapts a spiral configuration in flowing to outlet 25. If mixed gas flowing in a spiral flow is supplied at 30 m./sec.-70 m./sec. the velocity in the lengthwise direction of the flame holder 2 is extremely low, i.e., slower than the flame transmission velocity.

The extremely low velocity mixed gas G in spirally flowing in the lengthwise direction of the flame holder chamber 20 is ignited by the stable primary flame at position V. The flame created by this ignition will form a very stable spirally formed flame, i.e., the secondary flame.

On the other hand, the majority of the mixed gas G will pass through chamber 3 to position B of the burner unit 1, and be ignited by the secondary flame.

The secondary flame flows in a slow stable spiral so that when it flows out of the flame holder chamber 20 it will show a uniform dispersion at position B and ignite uniformly the mixed gas G coming from chamber 3.

The stable flame ignited by the secondary flame burns continuously Within the combustion chamber 4. Because a stable spiral flame exists in the flame holder chamber 20 the flame in combustion chamber 4 maintains stable combustion with position B burning source in gas burner unit 1.

By providing a stable combustion source at position B, even though the majority of the mixed gas G is supplied to the combustion chamber in an unburned state, the mixed gas from each gas burner unit 1 will burn simultaneously at outlet 8 of combustion chamber 4. 0n the other hand, the mixed gas flow commences combustion from its interior. The outer portion of this mixed gas flow which covers the inner walls of combustion chamber 4, is the last to burn. Thus the refractory material is protected and in this way the stable burning flame is ejected out of burner orifice 8 into stable jet flame blast 106. The burner of this invention also provides adequate counter measures to prevent back fire which quite often takes place in gas burners.

The velocity of the mixed gas passing through holes 21, small holes 22 and hole group 31 will be faster than the flame transmission velocity. Thus, the flame will never pass through these holes and enter cylindrical body 30.

Also when the majority of mixed gas G flows into combustion chamber 4, the gas will flow along the outside of flame holder 2 to cool it and prevent the flame holder from being heated even though combustion is taking place in chamber 20. For this reason the primary and secondary flames do not heat the flame holder sufliciently to cause ignition of the mixed gas before entering flame holder chamber 20.

When combustion takes place continuously in combustion chamber 4, the temperature of gas burner unit 1 will gradually rise until the ignition temperature of 600 C. of the mixed gas at holes 31 is reached at which point combustion will shift its position to holes 31 and the flame will not only be unstable but the gas burner unit 1 will break if made, for example, from cast iron.

To avoid this a water cooling tube 9 is provided between the combustion chamber 4 and gas burner unit 1. The size and water volume of the water cooling tube 9 is designed to maintain the small holes 31 at a temperature of less than 500 C. Thus the small hole group 31 does not function to maintain the flame as a combustion source. As previously mentioned, the combustion source exists at the position B. The small hole group 31 provides mixed gas G uniformly into chamber 3 thereby permitting walls 30 at the small hole group 31 to be thin.

In a normal gas burner the so-called beehive screen is employed to prevent back fire and obtain stable flame. To accomplish this the beehive screen hole diameters are less than 6 mm. with the screen wall thickness being over about 15 mm. If these conditions are not observed the screen will not serve its purpose of preventing back fire and giving a stable flame.

With such a thick walled screen and small holes, the necessary amount of mixed gas to be supplied to the combustion chamber to have a 1750 C. jet blast over 300 m./sec. will necessitate a combustion chamber load of 20,000,000 Kcal./h.r.m. 50,000,000 Kcal./h.r.m. and compression air pressure of about 2 kg./cm. 0.5l kg./ cm.

In this invention, the mixed gas G is supplied to chamber 3 by small hole group 31 drilled through a thin wall of about 5 mm. This results in a requirement of about 0.2-0.4 kg./cm. compressed air pressure. Because of this comparatively low compression pressure, the investment in equipment is less and the power expenses are reduced tremendously.

As explained above, the burner unit of this invention does not back fire, makes less noise, and ejects a stable jet blast. Thus, by arranging multiple burner units, it becomes possible to increase the flame width and the jet burner orifice width. It also is possible to obtain a uniformly distributed jet flame of 1750 C. with more than 300 m./sec. high velocity, at a total flame width of from 300-1200 mm. For a total flame width as previously mentioned, one can go to a wider flame only if it is possible to eliminate the combustion chamber 4 structural limitations. Further, with the method and apparatus of this invention gas burner fiberizing efliciency is promoted at less cost in equipment and power.

What is claimed is:

1. A method for generating a jet flame to fiberize glass filaments which comprises dividing a combustible mixed gas source into three streams, subdividing the first stream further into a plurality of additional streams which converge at a point to dissipate their kinetic energy, igniting the confluence, flowing the second stream in a spiral configuration around said ignited confluence to in turn be ignited to form a flame in stable form, flowing the third stream in a tubular configuration about said other two streams in the direction of their flow whereby the inner portion of the tubular stream is first ignited by said flame and ejecting the confluence of all of said streams through an orifice of smaller cross-section than that of said tubular stream at its greatest crosssection.

2. The method of claim 1 wherein said jet flame is widened by rendering contiguous at least two of said ejected ignited streams.

3. A method for generating a jet flame to fiberize glass filaments which comprises dividing a combustible mixed gas source into three streams, subdividing the first stream further into a plurality of additional streams which converge at a point to dissipate their kinetic energy, igniting the confluence, flowing the second stream in a spiral configuration around said ignited confluence to in turn be ignited to form a flame in stable form, flowing the third stream in a tubular configuration about said other two streams in the direction of their flow whereby the inner portion of the tubular stream is first ignited by said flame, ejecting the confluence of all of said streams through an orifice of smaller cross-section than that of said tubular stream at its greatest cross-section and passing glass filaments into the ejected ignited stream substantially normal to the direction of flow of said ignited stream.

4. An apparatus to generate a jet flame to fiberize glass filaments comprising a flame holder having orifices in one end thereof to which an igniter is fixed, the orifices of said end enabling combustible gas to pass through the end of the holder into the interior thereof to be ignited by said igniter, said flame holder defining holes in a wall other than the end to create a spiral configuration to gases flowing therethrough into the interior of said holder and around said first gases entering from said orifices, conduit means having one end in contact with the flame holder and the other end connected to a gas supply source, said conduit defining a plurality of holes near the flame holder, a main body means secured to said conduit and surrounding said conduit to define a chamber therebetween, a combustion chamber communicating with said chamber and having an exit through which a high temperature and a high velocity flame is ejected.

5. The apparatus of claim 4 wherein a plurality of main body means are in communication with said combustion chamber in a side by side relation.

6. The apparatus of claim 4 wherein the orifices passing through the end of the flame holder are directed to converge to a point immediately in front of the igniter.

7. The apparatus of claim 4 wherein said flame holder is cylindrical and the holes in the cylindrical wall are tangentially positioned.

8. The apparatus of claim 4 wherein said conduit means is a pipe and said holes are positioned normal to the pipe wall.

9. The apparatus of claim 4 wherein said main body means is cylindrical and is attached to said combustion chamber through a heat exchange means.

10. An apparatus to generate a jet flame to fiberize glass filaments comprising a cylindrical flame holder having orifices in one end thereof to which an igniter is fixed, the orifices ofsaid end enabling combustible gas to pass through the end of the holder into the interior thereof to be ignited by said igniter, said flame holder defining tangentially positioned holes in the cylinder Wall to create a spiral configuration to gases flowing therethrough into the interior of said holder and around said first gases entering from said orifices, a cylindrical mixed gas carrying pipe having one end in contact with the flame holder and the other end connected to a mixed gas supply source, said pipe defining a plurality of holes positioned normal to the pipe wall near the flame holder, a cylindrical main body secured to said pipe and surrounding said pipe to define a chamber therebetween, a heat exchange tube attached to said main body having an opening therethrough in alignment with said chamber and a combustion chamber attached to said heat exchange tube and in alignment with said opening of said heat exchange tube, said combustion chamber having an exit through which a high temperature and a high velocity flame is ejected.

11. An apparatus to fiberize glass filaments comprising an extrusion means for glass filaments, means to direct glass filaments into a jet flame and a gas burner, said gas burner comprising a cylindrical flame holder having orifices in one end thereof to which an igniter is fixed, the orifices of said end enabling combustible gas to pass through the end of the holder into the interior thereof to be ignited by said igniter, said flame holder defining tangentially positioned holes in the cylinder wall to create a spiral configuration to gases flowing therethrough into the interior of said holder and around said first gases entering from said orifices, a cylindrical mixed gas carrying pipe having one end in contact with the flame holder and the other end connected to a mixed gas supply source, said pipe defining a plurality of holes positioned normal to the pipe wall near the flame holder, a cylindrical main body secured to said pipe and surrounding said pipe to define a chamber therebetween, a heat exchange tube atached to said main body having an opening therethrough in alignment with said chamber and a combustion chamber attached to said heat exchange tube and in alignment with said opening of said heat exchange tube, said combustion chamber having an exit through which a high temperature and a high velocity flame is ejected.

References Cited UNITED STATES PATENTS 3,015,127 1/1962 Stalego 43 l--158 X 3,218,049 11/1965 Voorheis 431--8 X 3,418,060 12/1968 Spielman et al 431158 ROBERT L. LINDSAY, JR., Primary Examiner US. Cl. X.R. 

